1. Field of the Invention
The present invention relates to a method and apparatus for manufacturing a super abrasive cutting saw and, more particularly, to the method and apparatus for manufacturing a diamond cutting saw or a CBN cutting saw made by sintering a pressed powder including super abrasives such as fine diamond abrasives, cubic born nitride and the like around the periphery of an orbicular cutting saw plate.
2. Description of the Prior Art
Known methods for manufacturing such type of diamond cutting saw are the following method.
The first method is to press a powder including fine diamond abrasives together to form a moss of pressed powder into a prescribed shape in advance after forming two pressed powder masses having a same shape, a steel plate to be formed into a cutting saw plate is inserted between the two pressed powder masses in a mold and sintered. According to this method, a seam defined between the two pressed powder masses is flat and the outer surfaces of the masses are also formed substantially with a flat sinter.
The other method is to form a sheet of pressed powder into a prescribed shape with the powder including fine diamond abrasives in advance, which is sintered and at the same time, sintering the cutting saw plate by intruding it into the sintered portion formed by sintering the pressed powder sheet with its thermal expansion, and simultaneously fusing the sintered portion onto the cutting saw plate.
The first method, when forming each pressed powder mass, requires preparing each orbicular pressed powder mass having a flat surface and the masses are joined together to form a diamond layer with the two pressed powders masses by sintering. This causes some portions in a border between the two opposing pressed powder masses to be lacking diamond abrasives.
In the second method, such disadvantage of the first method is removed by forming a sheet of pressed powder in advance, since the larger the diameter and higher the temperature the larger the magnitude of intrusion of the cutting saw plate into the sintered portion with its thermal expansion. But the second method is unsuitable for manufacturing a relatively smaller cutting saw or when using a powder having a low sintering temperature. Also, the bonding strength between the sintered diamond and the cutting saw plate is relatively weaker so the latter diamond cutting saw is unsuitable as a cutting saw for use under severe conditions.